Heat transfer unit



1940- w. R. CLARKE HEAT TRENSFER UNIT 7 Filed Margh 9, 1940 Patented Oct. 8, 1940 v PATENT OFFICE HEAT TRANSFER UNIT Walter R. Clarke, Hartford, Conn., assignor to The Vulcan Radiator Company, Hartford, Conn., a corporation of Connecticut Application March 9, 1940, Serial No. 323,168

1 Claim.

This invention relates to heat transfer units and more particularly to those heating radiators of the type which comprises a central tubular metallic core with a plurality of spaced sheet metal fins secured thereon to provide extended radiating surfaces. The object of this invention is to so form fins for such radiators that not only will their radiating surfaces be more extended but the fiow of air over their surfaces will be more effective than is the case with the fins in common use of the same exterior contour and size.

In attaining the object of this invention each fin is stamped from thin sheet metal, preferably copper, alternatelyfrom opposite sides to form dome-shaped protuberances on one face and conforming cavities on the opposite face, and these fins are secured side by side, with small spaces between, on to a tubular core so that the protuberances on one fin are opposite the cavities on the adjacent fins. Fins so formed are stiffer and more rigid therefore can be made of thinner stock, and they provide greater radiating surfaces, as well as present a more ornamental effect when assembled, than smooth fins, suchas are shown in Patent No. 1,916,656, July 4, 1933, and what is of more particular value the alternating protuberances and cavities so effect and change the direction of and cause such circulation of the air currents as they pass over the surfaces between the fins that a maximum of radiation eificiency'is attained with a minimum amount of metal.

In the accompanying drawing Fig. 1 shows a side view of a portion of one section of a radiator witha few fins formed in accordance with this improvement.

Fig. 2 shows on larger scale a face view of th fin and section of the core.

Fig. 3 is a view looking at the left hand edge of Fig. 2. Fig. 4 is a view looking at the right hand edge of Fig. 2.

Fig. 5 is a section on line 5-5 on Fig. 2.

The unit shown has a central tubular core I which is commonly made of copper or similar good heat conducting metal of the required thickness, diameter and length. The fins 2 are stamped to shape from thin sheet metal, preferably copper, to any approved size and outline either rectangular or circular. The fins have a central perforation 3 and they are slipped upon and tightly secured to the core in a manner similar to that illustrated in Patent No. 1,646,384, Oct. 25, 1927.

The fins which form the subject of this invention are, in the areas beyond the central perforations. stamped from opposite sides to pro (Cl. 257-F-262) duce on each side protuberances 4 and cavities 5, the design being such that on one face of the fins the protuberances alternate with the cavities and on the opposite face the cavities alternate with the protuberances. The protuberances may be dome-shaped or cone-shaped, preferably the former, and the cavities substantially conform thereto. The protuberances may vary in size, and preferably they are located in close proximity on both sides, but if desired they could be on one side only.

Air flowing through a radiator providedwith sections having such fins as herein described has no straight paths, it passes easily but alternately over and around the protuberances and into and out of the cavities in very circuitous and agitated streams and takes off a maximum amount of heat from the thus extended areas of the fins. In fact it has been found that owing to the passages taken by the air streams the radiation effect is increased to a greater degree than is the increase in surface area produced by the protuberances.

It has been demonstrated in actual use that the efiiciency of radiators provided with sections having fins of the form described is greatly increased over the-efficiency of prior radiators of this type provided with the commonly used fins, and thus a smaller fin resulting in a smaller radiator may be used to produce the same radiation effect as the prior radiators.

The invention claimed is:

A heat exchange unit comprising a tubular core of high heat conducting capacity and a plurality of fins of high heat conducting capacity spaced upon and secured to said core, each of said fins having a central perforation fitting said core and having on both faces a plurality of rows of dome-shaped protuberances and conforming cavities which have contiguous circular perimeters, the protuberances and cavities in the line of air flow through the unit alternating with each other and the rows so related that the perimeters of the protuberances and cavities of one row interties diagonal to the line of air 'fiow, which rows 

